1. I would most certainly advise that you create a Lasting or Enduring Power of Attorney at this stage before it gets too late. Otherwise it will make dealing with your financial and personal welfare fraught with difficulty. I regret to say that your wife is correct in this instance. The difficulty with not having an Enduring or Lasting Power of ATtorney in place is that things like paying for your medical bills might be impossible. Similarly, there might be difficulties in making decisions about your care. I appreciate that you may be OK to deal with things at the moment. But with the progressive onset of the disease this will not be the case. So you need to prepare for that eventuality and set out a scheme within which decisions about you will be made. You cannot make one any longer once you loose your faculties. Such a Power of Attorney only kicks in once you loose your mind.
2. Until then, you wil handle your own affairs. It is only when you ar eno longer able to do so, that someone else authorised by the Power of Attorney will take over. Go and see a solicitor who will draft one up for you. Be aware that you will need additionally to have a psychiatrist in attendance to certify as to your mental capacity to make the Power of ATtorney.